1.
$Cu+2H_2SO_4\to CuSO_4+SO_2+2H_2O$
$2Ag+2H_2SO_4\to Ag_2SO_4+SO_2+2H_2O$
$n_{NaOH}=0,07.0,5=0,035 mol$
- TH1: chất rắn chứa $NaOH$
Gọi x là mol $SO_2$
$SO_2+2NaOH\to Na_2SO_3+H_2O$
$\Rightarrow n_{Na_2SO_3}=x; n_{NaOH\text{dư}}=0,035-2x$
$\Rightarrow 40(0,035-2x)+126x=3,435$
$\Leftrightarrow x=0,044$
Gọi a, b là mol Ag, Cu.
$\Rightarrow 108a+64b=4,32$ (1)
$n_{SO_2}=0,5a+b=0,044$ (2)
(1)(2)$\Rightarrow a=0,02; b=0,034$
$\%m_{Ag}=50\%$
$\%m_{Cu}=50\%$
- TH2: chất rắn không chứa $NaOH$
Gọi m, n là mol $Na_2SO_3$, $NaHSO_3$
$2NaOH+SO_2\to Na_2SO_3+H_2O$
$NaOH+SO_2\to NaHSO_3$
$\Rightarrow 126m+104n=3,435$ (3)
$n_{NaOH}=2m+n=0,035$ (4)
(3)(4)$\Rightarrow m=0,0025; n=0,03$
$\Rightarrow n_{SO_2}=0,0025+0,03=0,0325 mol$
Gọi a, b là mol Cu, Ag.
$\Rightarrow 64a+108b=4,32$ (*)
$n_{SO_2}=a+0,5b=0,0325$ (**)
(*)(**)$\Rightarrow a=0,017; b=0,029$
$\%m_{Cu}=25,19\%$
$\%m_{Ag}=74,81\%$
